Hemostasis valves are currently used on catheters for performing percutaneous transluminal coronary angioplasty (PTCA), as well as angiographic procedures, for example, where X-ray contrast fluid is inserted into the coronary artery.
In PTCA, stenotic regions of coronary blood vessels are dilated by advancing a dilatation catheter through blood vessels into the stenotic region. The dilatation catheter advances over a guide wire, which guide wire moves forward, followed by the catheter, followed by another advance of the guide wire, etc. The guide wire-dilatation catheter system may be introduced through a guiding catheter to facilitate its placement.
To prevent the leakage of blood out of the proximal end of the catheter, a hemostasis valve is provided at the proximal end, to prevent seepage of blood between the guide wire and the catheter. For example, currently, numerous types of hemostasis valves are known. See for example Stevens, U.S. Pat. No. 4,000,739. Another design of hemostasis valve is the Tuohy-Borst type, making use of an adJustable, compressive sleeve which is axially compressed about the guide wire that it seals by means of a two-piece, screw threaded housing. Other designs may use an "O" ring and a tapered seat instead of a sleeve.
Many designs require tightening of the valve when high pressure X-ray contrast fluid or the like is run through the catheter. However, with such high pressure sealing, the guide wire cannot be advanced in effective manner, so the valve, such as a Tuohy-Borst valve, must be loosened so that the operator can "feel" any resistance encountered by the forward advancement of the guide wire, during the operation of advancing the guide wire through blood vessels.
The degree of loosening of the valve can be critical. If excessively loosened, low pressure leakage may occur. If loosened too little, the guide wire cannot be effectively advanced. Accordingly, it turns out that for the most effective performance of PTCA and angiography procedures, a hemostasis valve which is highly controllable is needed, so that the guide wire can be easily advanced, while low pressure leakage is prevented on an easy, reliable basis, without the need for great skill and experience in operation of the valve.
By this invention, a hemostasis valve is provided with reliable sealing against low pressure leakage around a guide wire or the like. At the same time an adjustable seal is also provided which may be adjusted to seal against high pressures. Accordingly, the adjustable seal may be applied or released as desired, but, preferably, a low pressure seal may be constantly present to stop leakage upon release of the high pressure seal. Thus, manipulation of the high pressure seal is less critical, and requires less skill in order to avoid leakage.
Also, the surgeon who is manipulating a typical catheter for entering coronary blood vessels, for example, is overburdened with respect to things to hold and manipulate during this process. By this invention, improved efficiency of adjustment of the adjustable valve of this invention may be provided to relieve the burden on the surgeon.